Abstract
Scouring-rushes (Equisetum sg. Hippochaete) are a group of horsetails with perennial aerial shoots strongly encrusted in silica. Accordingly, they seem to resist attacks from most herbivorous insects. Michelsen (2008) speculated that larval development of the European Pegomya terminalis (Rondani) and related anthomyiids takes place in specific scouring-rushes. Presently, we document that the larvae of two North American species related to P. terminalis attack developing shoots of Common scouring-rush, Equisetum hyemale L. Both species, Pegomya disticha Griffiths and P. cedrica Huckett, were found to coexist in a population of scouring-rush in Oklahoma. Various aspects of the life-history and morphology (3rd instar larva, male and female adults) for both species are described and documented by photos.
References
Griffiths, G.C.D. (1983a) Anthomyiidae [part]. In: Griffiths, G.C.D. (Ed.), Flies of the Nearctic Region 8 (2). 2. E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, pp. 161–288.
Griffiths, G.C.D. (1983b) Anthomyiidae [part]. In: Griffiths, G.C.D. (Ed.), Flies of the Nearctic Region 8 (2). 3. E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, pp. 289–408.
Hauke, R. L. (1963) A taxonomic monograph of the genus Equisetum subgenus Hippochaete. Nova Hedwigia, 8 (Beihefte), 1–123.
https://doi.org/10.2307/1546980
Hauke, R. L. (1978) A taxonomic monograph of the genus Equisetum subgenus Equisetum. Nova Hedwigia, 30, 385‒455.
https://doi.org/10.1127/nova.hedwigia/30/1979/385
Hauke, R.L. (1983) Horsetails (Equisetum) in North America. Fiddlehead Forum, 10, 39‒42.
Huckett, H.C. (1939) Descriptions of new North American Anthomyiidae belonging to the genus Pegomyia (Diptera). Transactions of the American Entomological Society, 65, 1‒37, 3 pls.
Huckett, H.C. (1941) A revision of the North American species belonging to the genus Pegomyia (Diptera: Muscidae). Memoirs of the American Entomological Society, 10, 1–131, 9 pls.
Husby, C. (2013) Biology and functional ecology of Equisetum with emphasis on the giant horsetails. The Botanical Review, 79, 147‒177.
https://doi.org/10.1007/s12229-012-9113-4
Michelsen, V. (1988) Taxonomy of the species of Pegomya (Diptera: Anthomyiidae) developing in the shoots of spurges (Euphorbia spp.). Entomologica scandinavica, 18, 425‒435.
https://doi.org/10.1163/187631287X00232
Michelsen, V. (2008) The Palaearctic species of the Pegomya terminalis species group (Diptera: Anthomyiidae), with descriptions of two new species. Zootaxa, 1781 (1), 31‒46.
https://doi.org/10.11646/zootaxa.1781.1.3
Knie, N., Fischer, S., Grewe, F., Polsakiewicz, M. & Knoop, V. (2015) Horsetails are the sister group to all other monilophytes and Marattiales are sister to leptosporangiate ferns. Molecular Phylogenetics and Evolution, 90, 140‒149.
https://doi.org/10.1016/j.ympev.2015.05.008
Poinar, Jr.,G. (2014) Insect herbivores of horsetails. Bionomics, dispersal and co-evolution. American Entomologist, 60, 235‒240.
https://doi.org/10.1093/ae/60.4.235
Rai, H.S. & Graham, S.W. (2010) Utility of a large, multigene plastid data set in inferring higher-order relationships in ferns and relatives (Monilophytes). American Journal of Botany, 97, 1444‒1456.
https://doi.org/10.3732/ajb.0900305
Rothfels, C.J., Li, F.W., Sigel, E.M., Huiet, L., Larsson, A., Burge, D.O., Ruhsam, M., Deyholos, M., Soltis, D.E., Stewart, Jr.C.N., Shaw, S.W., Pokorny, L., Chen, T., dePamphilis, C., DeGironimo, L., Chen, L., Wei, X., Sun, X., Korall, P., Stevenson, D.W., Graham, S.W., Wong, G.K.-S. & Pryer, K.M. (2015) The evolutionary history of ferns inferred from 25 low-copy nuclear genes. American Journal of Botany, 102, 1089‒1107.
https://doi.org/10.3732/ajb.1500089
Suwa, M. (2000) A revision of the chinensis group of Pegomya in Japan (Diptera: Anthomyiidae). Insecta matsumurana, New Series, 57, 89‒127.